Messages in this thread | | | Date | Sat, 12 Dec 2009 14:24:28 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC] Fix 2.6.33 x86 regression to kgdb hw breakpoints - due to perf API changes |
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* Jason Wessel <jason.wessel@windriver.com> wrote:
> I'll lead with a question. Are the people making the Perf API changes > booting allyesconfig kernels? > > The regression tests built into the kernel for kgdb fail as a result > of the perf API changes and can result in a hard kernel hang. > > My hope would have been that someone would have reported the problem, > created a patch to disable the test that hangs the kernel, or to fix > kgdb such that it works with the API changes. Likewise, if there are > tests I should run to regression test the changes to the perf API, I > would like to know since we all want to make use of the same hw > resource. > > A patch has been included in this mail which allows kgdb to pass the > internal regression tests for hw breakpoints. I would like to get > some comments or start a discussion as to how to solve this problem in > the 2.6.33 cycle, as it is a regression in functionality.
Hm, the kgdb hw-breakpoint changes freshly put into v2.6.33 look pretty broken: they access the raw hw registers and ignore the higher level abstraction. Your patch still uses way too low level primitives. Please use the highlevel abstraction: register/unregister_wide_hw_breakpoint() should do the trick. (if there's any changes/extensions needed to it then please let us know about it.)
If that's too much for v2.6.33 then i guess we need to revert or disable the kgdb hw-breakpoint changes for now.
Thanks,
Ingo
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